Implement a Non-Blocking Child Process Interface

.lune/hello_lune.luau

@@ -129,7 +129,7 @@ end
 ]]
 
 print("Sending 4 pings to google 🌏")
-local result = process.spawn("ping", {
+local result = process.exec("ping", {
 	"google.com",
 	"-c 4",
 })

crates/lune-std-process/Cargo.toml

@@ -20,6 +20,9 @@ directories = "5.0"
 pin-project = "1.0"
 os_str_bytes = { version = "7.0", features = ["conversions"] }
 
+bstr = "1.9"
+bytes = "1.6.0"
+
 tokio = { version = "1", default-features = false, features = [
     "io-std",
     "io-util",

crates/lune-std-process/src/lib.rs

@@ -1,27 +1,33 @@
 #![allow(clippy::cargo_common_metadata)]
 
 use std::{
+    cell::RefCell,
     env::{
         self,
         consts::{ARCH, OS},
     },
     path::MAIN_SEPARATOR,
     process::Stdio,
+    rc::Rc,
+    sync::Arc,
 };
 
 use mlua::prelude::*;
 
 use lune_utils::TableBuilder;
 use mlua_luau_scheduler::{Functions, LuaSpawnExt};
+use options::ProcessSpawnOptionsStdio;
 use os_str_bytes::RawOsString;
-use tokio::io::AsyncWriteExt;
+use stream::{ChildProcessReader, ChildProcessWriter};
+use tokio::{io::AsyncWriteExt, process::Child, sync::RwLock};
 
 mod options;
+mod stream;
 mod tee_writer;
 mod wait_for_child;
 
 use self::options::ProcessSpawnOptions;
-use self::wait_for_child::{wait_for_child, WaitForChildResult};
+use self::wait_for_child::wait_for_child;
 
 use lune_utils::path::get_current_dir;
 
@@ -73,7 +79,8 @@ pub fn module(lua: &Lua) -> LuaResult<LuaTable> {
         .with_value("cwd", cwd_str)?
         .with_value("env", env_tab)?
         .with_value("exit", process_exit)?
-        .with_async_function("spawn", process_spawn)?
+        .with_async_function("exec", process_exec)?
+        .with_function("create", process_create)?
         .build_readonly()
 }
 
@@ -141,11 +148,16 @@ fn process_env_iter<'lua>(
     })
 }
 
-async fn process_spawn(
+async fn process_exec(
     lua: &Lua,
     (program, args, options): (String, Option<Vec<String>>, ProcessSpawnOptions),
 ) -> LuaResult<LuaTable> {
-    let res = lua.spawn(spawn_command(program, args, options)).await?;
+    let res = lua
+        .spawn(async move {
+            let cmd = spawn_command_with_stdin(program, args, options.clone()).await?;
+            wait_for_child(cmd, options.stdio.stdout, options.stdio.stderr).await
+        })
+        .await?;
 
     /*
         NOTE: If an exit code was not given by the child process,
@@ -168,30 +180,104 @@ async fn process_spawn(
         .build_readonly()
 }
 
-async fn spawn_command(
+#[allow(clippy::await_holding_refcell_ref)]
+fn process_create(
+    lua: &Lua,
+    (program, args, options): (String, Option<Vec<String>>, ProcessSpawnOptions),
+) -> LuaResult<LuaTable> {
+    // We do not want the user to provide stdio options for process.create,
+    // so we reset the options, regardless of what the user provides us
+    let mut spawn_options = options.clone();
+    spawn_options.stdio = ProcessSpawnOptionsStdio::default();
+
+    let (code_tx, code_rx) = tokio::sync::broadcast::channel(4);
+    let code_rx_rc = Rc::new(RefCell::new(code_rx));
+
+    let child = spawn_command(program, args, spawn_options)?;
+
+    let child_arc = Arc::new(RwLock::new(child));
+
+    let child_arc_clone = Arc::clone(&child_arc);
+    let mut child_lock = tokio::task::block_in_place(|| child_arc_clone.blocking_write());
+
+    let stdin = child_lock.stdin.take().unwrap();
+    let stdout = child_lock.stdout.take().unwrap();
+    let stderr = child_lock.stderr.take().unwrap();
+
+    let child_arc_inner = Arc::clone(&child_arc);
+
+    // Spawn a background task to wait for the child to exit and send the exit code
+    let status_handle = tokio::spawn(async move {
+        let res = child_arc_inner.write().await.wait().await;
+
+        if let Ok(output) = res {
+            let code = output.code().unwrap_or_default();
+
+            code_tx
+                .send(code)
+                .expect("ExitCode receiver was unexpectedly dropped");
+        }
+    });
+
+    TableBuilder::new(lua)?
+        .with_value("stdout", ChildProcessReader(stdout))?
+        .with_value("stderr", ChildProcessReader(stderr))?
+        .with_value("stdin", ChildProcessWriter(stdin))?
+        .with_async_function("kill", move |_, ()| {
+            // First, stop the status task so the RwLock is dropped
+            status_handle.abort();
+            let child_arc_clone = Arc::clone(&child_arc);
+
+            // Then get another RwLock to write to the child process and kill it
+            async move { Ok(child_arc_clone.write().await.kill().await?) }
+        })?
+        .with_async_function("status", move |lua, ()| {
+            let code_rx_rc_clone = Rc::clone(&code_rx_rc);
+            async move {
+                // Exit code of 9 corresponds to SIGKILL, which should be the only case where
+                // the receiver gets suddenly dropped
+                let code = code_rx_rc_clone.borrow_mut().recv().await.unwrap_or(9);
+
+                TableBuilder::new(lua)?
+                    .with_value("code", code)?
+                    .with_value("ok", code == 0)?
+                    .build_readonly()
+            }
+        })?
+        .build_readonly()
+}
+
+async fn spawn_command_with_stdin(
     program: String,
     args: Option<Vec<String>>,
     mut options: ProcessSpawnOptions,
-) -> LuaResult<WaitForChildResult> {
-    let stdout = options.stdio.stdout;
-    let stderr = options.stdio.stderr;
+) -> LuaResult<Child> {
     let stdin = options.stdio.stdin.take();
 
-    let mut child = options
-        .into_command(program, args)
-        .stdin(if stdin.is_some() {
-            Stdio::piped()
-        } else {
-            Stdio::null()
-        })
-        .stdout(stdout.as_stdio())
-        .stderr(stderr.as_stdio())
-        .spawn()?;
+    let mut child = spawn_command(program, args, options)?;
 
     if let Some(stdin) = stdin {
         let mut child_stdin = child.stdin.take().unwrap();
         child_stdin.write_all(&stdin).await.into_lua_err()?;
     }
 
-    wait_for_child(child, stdout, stderr).await
+    Ok(child)
+}
+
+fn spawn_command(
+    program: String,
+    args: Option<Vec<String>>,
+    options: ProcessSpawnOptions,
+) -> LuaResult<Child> {
+    let stdout = options.stdio.stdout;
+    let stderr = options.stdio.stderr;
+
+    let child = options
+        .into_command(program, args)
+        .stdin(Stdio::piped())
+        .stdout(stdout.as_stdio())
+        .stderr(stderr.as_stdio())
+        .spawn()?;
+
+    Ok(child)
 }

crates/lune-std-process/src/stream.rs

@@ -0,0 +1,58 @@
+use bstr::BString;
+use bytes::BytesMut;
+use mlua::prelude::*;
+use tokio::io::{AsyncRead, AsyncReadExt, AsyncWrite, AsyncWriteExt};
+
+const CHUNK_SIZE: usize = 8;
+
+#[derive(Debug, Clone)]
+pub struct ChildProcessReader<R: AsyncRead>(pub R);
+#[derive(Debug, Clone)]
+pub struct ChildProcessWriter<W: AsyncWrite>(pub W);
+
+impl<R: AsyncRead + Unpin> ChildProcessReader<R> {
+    pub async fn read(&mut self, chunk_size: Option<usize>) -> LuaResult<Vec<u8>> {
+        let mut buf = BytesMut::with_capacity(chunk_size.unwrap_or(CHUNK_SIZE));
+        self.0.read_buf(&mut buf).await?;
+
+        Ok(buf.to_vec())
+    }
+
+    pub async fn read_to_end(&mut self) -> LuaResult<Vec<u8>> {
+        let mut buf = vec![];
+        self.0.read_to_end(&mut buf).await?;
+
+        Ok(buf)
+    }
+}
+
+impl<R: AsyncRead + Unpin + 'static> LuaUserData for ChildProcessReader<R> {
+    fn add_methods<'lua, M: LuaUserDataMethods<'lua, Self>>(methods: &mut M) {
+        methods.add_async_method_mut("read", |lua, this, chunk_size: Option<usize>| async move {
+            let buf = this.read(chunk_size).await?;
+
+            if buf.is_empty() {
+                return Ok(LuaValue::Nil);
+            }
+
+            Ok(LuaValue::String(lua.create_string(buf)?))
+        });
+
+        methods.add_async_method_mut("readToEnd", |lua, this, ()| async {
+            Ok(lua.create_string(this.read_to_end().await?))
+        });
+    }
+}
+
+impl<W: AsyncWrite + Unpin> ChildProcessWriter<W> {
+    pub async fn write(&mut self, data: BString) -> LuaResult<()> {
+        self.0.write_all(data.as_ref()).await?;
+        Ok(())
+    }
+}
+
+impl<W: AsyncWrite + Unpin + 'static> LuaUserData for ChildProcessWriter<W> {
+    fn add_methods<'lua, M: LuaUserDataMethods<'lua, Self>>(methods: &mut M) {
+        methods.add_async_method_mut("write", |_, this, data| async { this.write(data).await });
+    }
+}

crates/lune/src/tests.rs

@@ -138,13 +138,16 @@ create_tests! {
     process_cwd: "process/cwd",
     process_env: "process/env",
     process_exit: "process/exit",
-    process_spawn_async: "process/spawn/async",
-    process_spawn_basic: "process/spawn/basic",
-    process_spawn_cwd: "process/spawn/cwd",
-    process_spawn_no_panic: "process/spawn/no_panic",
-    process_spawn_shell: "process/spawn/shell",
-    process_spawn_stdin: "process/spawn/stdin",
-    process_spawn_stdio: "process/spawn/stdio",
+    process_exec_async: "process/exec/async",
+    process_exec_basic: "process/exec/basic",
+    process_exec_cwd: "process/exec/cwd",
+    process_exec_no_panic: "process/exec/no_panic",
+    process_exec_shell: "process/exec/shell",
+    process_exec_stdin: "process/exec/stdin",
+    process_exec_stdio: "process/exec/stdio",
+    process_spawn_non_blocking: "process/create/non_blocking",
+    process_spawn_status: "process/create/status",
+    process_spawn_stream: "process/create/stream",
 }
 
 #[cfg(feature = "std-regex")]

scripts/generate_compression_test_files.luau

@@ -108,7 +108,7 @@ local BIN_ZLIB = if process.os == "macos" then "/opt/homebrew/bin/pigz" else "pi
 
 local function checkInstalled(program: string, args: { string }?)
 	print("Checking if", program, "is installed")
-	local result = process.spawn(program, args)
+	local result = process.exec(program, args)
 	if not result.ok then
 		stdio.ewrite(string.format("Program '%s' is not installed\n", program))
 		process.exit(1)
@@ -123,7 +123,7 @@ checkInstalled(BIN_ZLIB, { "--version" })
 -- Run them to generate files
 
 local function run(program: string, args: { string }): string
-	local result = process.spawn(program, args)
+	local result = process.exec(program, args)
 	if not result.ok then
 		stdio.ewrite(string.format("Command '%s' failed\n", program))
 		if #result.stdout > 0 then

tests/datetime/formatLocalTime.luau

@@ -31,7 +31,7 @@ if not runLocaleTests then
 	return
 end
 
-local dateCmd = process.spawn("bash", { "-c", "date +\"%A, %d %B %Y\" --date='@1693068988'" }, {
+local dateCmd = process.exec("bash", { "-c", "date +\"%A, %d %B %Y\" --date='@1693068988'" }, {
 	env = {
 		LC_ALL = "fr_FR.UTF-8 ",
 	},

tests/process/create/kill.luau

@@ -0,0 +1,21 @@
+local process = require("@lune/process")
+
+-- Killing a child process should work as expected
+
+local message = "Hello, world!"
+local child = process.create("cat")
+
+child.stdin:write(message)
+child.kill()
+
+assert(child.status().code == 9, "Child process should have an exit code of 9 (SIGKILL)")
+
+assert(
+	child.stdout:readToEnd() == message,
+	"Reading from stdout of child process should work even after kill"
+)
+
+local stdinWriteOk = pcall(function()
+	child.stdin:write(message)
+end)
+assert(not stdinWriteOk, "Writing to stdin of child process should not work after kill")

tests/process/create/non_blocking.luau

@@ -0,0 +1,13 @@
+local process = require("@lune/process")
+
+-- Spawning a child process should not block the thread
+
+local childThread = coroutine.create(process.create)
+
+local ok, err = coroutine.resume(childThread, "echo", { "hello, world" })
+assert(ok, err)
+
+assert(
+	coroutine.status(childThread) == "dead",
+	"Child process should not block the thread it is running on"
+)

tests/process/create/status.luau

@@ -0,0 +1,15 @@
+local process = require("@lune/process")
+
+-- The exit code of an child process should be correct
+
+local randomExitCode = math.random(0, 255)
+local isOk = randomExitCode == 0
+local child = process.create("exit", { tostring(randomExitCode) }, { shell = true })
+local status = child.status()
+
+assert(
+	status.code == randomExitCode,
+	`Child process exited with wrong exit code, expected {randomExitCode}`
+)
+
+assert(status.ok == isOk, `Child status should be {if status.ok then "ok" else "not ok"}`)

tests/process/create/stream.luau

@@ -0,0 +1,18 @@
+local process = require("@lune/process")
+
+-- Should be able to write and read from child process streams
+
+local msg = "hello, world"
+
+local catChild = process.create("cat")
+catChild.stdin:write(msg)
+assert(
+	msg == catChild.stdout:read(#msg),
+	"Failed to write to stdin or read from stdout of child process"
+)
+
+local echoChild = if process.os == "windows"
+	then process.create("/c", { "echo", msg, "1>&2" }, { shell = "cmd" })
+	else process.create("echo", { msg, ">>/dev/stderr" }, { shell = true })
+
+assert(msg == echoChild.stderr:read(#msg), "Failed to read from stderr of child process")